1. Field of the Invention
The present invention relates to a polarizing plate, a display panel having the polarizing plate, and a display device having the polarizing plate. More particularly, the present invention relates to a polarizing plate limiting a reduction of a polarized transmission rate over time, a display panel having the polarizing plate, and a display device having the polarizing plate.
2. Description of the Related Art
Generally, a liquid crystal display (“LCD”) device includes an LCD panel and a backlight assembly. The LCD panel includes a thin-film transistor (“TFT”) substrate, a color filter substrate and a liquid crystal layer interposed between the TFT substrate and the color filter substrate. The LCD panel does not self-emit light, so that the backlight assembly mainly influences the luminance of an image that is displayed on the LCD panel.
The LCD device further includes two polarizing plates disposed on and under the LCD panel so that the liquid crystal layer serves as a light shutter. The polarizing plate transmits light polarized in a predetermined direction. For example, the polarizing plate is theoretically capable of transmitting about 50% of light generated by the backlight assembly. However, practically, about 43% of the light generated by the backlight assembly is transmitted because of light lost at the polarizing plate.
Furthermore, manufacturing costs of the polarizing plate take up about 25% to about 30% of total manufacturing costs of the LCD panel having the polarizing plate, thereby increasing the manufacturing costs of the LCD device.
When, a conductive lattice pattern has a plurality of conductive lattice lines that are arranged in a stripe shape and have a nano-sized width and a nano-sized pitch, the conductive lattice pattern has a reflecting capacity and a degree of polarization substantially the same as a dual brightness enhancement film (“DBEF”). However, the conductive lattice pattern has a polarizing degree of about 1,000:1, which is higher than a polarizing degree of the DBEF. Thus, the conductive lattice pattern is capable of replacing a conventional polarizing plate.
The conductive lattice lines of the conductive lattice pattern are formed on a base layer such as a glass substrate, polyethylene terephthalate (“PET”), etc. The conductive lattice lines may be formed using a material having a relatively high light-reflecting rate and a relatively low light-absorbing rate such as silver (Ag), aluminum (Al), etc.
However, when a polarizing plate having the conductive lattice lines formed thereon is used for a long time, high-energy light such as ultraviolet (“UV”) light is absorbed so that the temperature of the conductive lattice lines is increased. As a result, an adhesive force of the conductive lattice lines and the base layer may be decreased, and a light-reflecting rate of the conductive lattice lines may be decreased. Therefore, a polarized transmission rate of the polarizing plate may be decreased and the lifetime of the polarizing plate may be reduced.